1. Field of the Invention
The present invention relates to an electrophotographic image forming apparatus such as an electrophotographic copier, a printer, a facsimile device, and a compound device thereof, and more particularly to a developer replenishing device suitable for use in this image forming apparatus.
2. Description of the Related Art
In an electrophotographic image forming apparatus, an image is typically created by forming a toner image using a so-called developer containing a toner and a carrier. The toner is steadily consumed as image formation progresses, and therefore a toner storage container serving as a toner cartridge filled with toner is generally used, and when all of the toner in the toner storage container has been consumed, new toner is supplied by replacing the toner storage container with a new toner storage container.
Since toner is a powder, it is important to discharge the toner such that as little toner as possible remains in the toner storage container. Conventional methods for conveying toner from the interior of the container to a container outlet portion include a method of providing a screw known as an auger in the interior of the container and conveying the toner in a single direction by rotating the screw, a method of providing a spiral projection known as a screw bottle on the inner surface of a cylindrical portion of a tubular container and rotating the container such that the toner is conveyed little by little to an outlet portion of the container, and so on.
The present inventor has proposed a method of discharging toner from a toner storage container by applying acceleration to the toner storage container through an asymmetric reciprocating motion such that the toner in the container is moved in a single direction by inertia and discharged through a discharge port provided in the downward direction of the container.
In the toner conveyance method employing an auger, a member must be provided in the interior of the container and rotated, and therefore the structure of the container becomes complicated. In the toner conveyance method employing a screw bottle, no member need be provided in the interior of the container, and therefore the structure of the container is simple, but since the container is rotated, the container must be formed with a cylindrical main body and provided with an outlet in one end surface (the shape of a normal bottle laid on its side). Hence, in comparison with a rectangular parallelepiped-shaped container, the amount of toner that can be stored in the container is small, the container is not easy to hold and may slip out of the hand during replacement, and so on.
Meanwhile, with the method of applying a reciprocating motion (in the lateral direction) to the container to move the toner inside the container such that the toner is discharged through a discharge port provided in the lower side of the container (to be referred to hereafter as a reciprocation method) a simple container shape such as a rectangular parallelepiped that can hold a large amount of toner (that has little dead space) may be employed, and since there is no need to provide a conveyor member inside the container, a low-cost, compact replenishing device can be realized. Moreover, a bag-shaped container constituted by a flexible sheet may be used, enabling savings in natural resources and costs.
However, a reciprocation type replenishing device is greatly disadvantaged in that the resultant vibration causes abnormal images (banding). Hence, to cancel out the effect of vibration generated during reciprocation of the container on the main body, a method of providing a movable stopper and causing the container and stopper to collide at opposite phase speeds has been proposed. However, even slight vibration affects image formation, and therefore a replenishment method in which vibration is reduced to the greatest extent possible is required.
Meanwhile, during image formation, residual toner is generated following transfer, and conventionally, this residual toner is recovered in a recovery bottle. A method of provided the container with a recovery chamber in advance and recovering the residual toner in the container has also been proposed, but when this method is employed, the constitution of a residual toner moving device and the capacity of the container decrease, and the cost of the container rises due to its complexity. It is therefore difficult to incorporate this method into an actual product.
Technologies relating to the present invention are also disclosed in, e.g., Japanese Unexamined Patent Application Publication 2003-098813, Japanese Unexamined Patent Application Publication 2005-292300, Japanese Unexamined Patent Application Publication S63-010424, and Japanese Unexamined Patent Application Publication 2002-148924.